1. Field of the Invention
The present invention relates to a method for designing, a method for producing and an injection molding device, for a resin product molded by injection molding.
2. Related Background Art
When molding resin using an injection molding device, it is necessary to determine the resin for use, the molding temperature, the injection speed, and others so that the mold clamping force required for molding does not exceed the capacity of the device. Normally the predetermined mold clamping force of a device is not the minimum necessary force for molding but a value including safety factor allowance is used. The mold clamping force is expressed by [(the resin pressure in the cavity)×(the projected area)]. For example, Japanese Patent Laid-open Gazette No. 2002-355866, page 2 discloses a technology to reduce the mold clamping force.
Above-mentioned Gazette discloses a technology, in the case where the product shape extends in a longitudinal direction, that a plurality of gates through which the molten resin is injected into the cavity are arranged along the direction from the resin filling starting side to the filling completion side, and the molten resin is sequentially injected into the cavity at a specified interval starting with injection at the filling starting gate. According to the technology, the resin injected in early stage comes to an almost cooled and solidified state when reached the final filling stage. As a result, the substantial projected area which should be filled with the molten resin injected from the final gate is significantly reduced compared with the total projected area of the cavity.